Boundary Layer between a Plasma and a Magnetic Field
Boundary Layer between a Plasma and a Magnetic Field
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等离子体和磁场之间的边界层
DOI：
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发表时间：
1961
期刊：
影响因子：
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通讯作者：
H. Grad
中科院分区：
文献类型：
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作者：
H. Grad
考虑了等离子体与磁场之间的稳定边界层或鞘层问题。发现了一个自洽过渡层，它将正无穷远处的均匀磁场与负无穷远处具有任意速度分布的无碰撞无场等离子体区连接起来；也就是说，发现了这样一个磁场轮廓，即在这个磁场中精确的粒子轨道产生电流，从而产生磁场。“最薄”解的一个有趣的数学特征是，在负无穷远的任何非奇异速度分布下，尽管等离子体扩展到无穷远，呈指数衰减，进入磁场区域，但磁场只穿透等离子体有限的距离。长度的尺度是光速与等离子体频率之比，或者等价地，代表粒子的拉莫尔半径。在不同质量粒子的情况下，电荷分离产生的电场可以忽略不计。
The problem of a steady boundary layer or sheath between a plasma and a magnetic field is considered. A self‐consistent transition layer is found which joins a uniform magnetic field at plus infinity with a collisionless field‐free plasma region with arbitrary velocity distribution at minus infinity; i.e., a magnetic field profile is found such that the exact particle orbits in this field produce a current which gives rise to the field. An interesting mathematical feature of the ``thinnest'' such solution is that, with any nonsingular velocity distribution at minus infinity, the magnetic field penetrates only a finite distance into the plasma although the plasma extends to infinity, exponentially attenuated, into the magnetic field region. The scale of length is the ratio of the speed of light to the plasma frequency or, equivalently, the Larmor radius of a representative particle. Electric fields arising from charge separation in the case of particles of different mass are ignored.